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  Subjects -> ENGINEERING (Total: 1963 journals)
    - CHEMICAL ENGINEERING (151 journals)
    - CIVIL ENGINEERING (149 journals)
    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1120 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CHEMICAL ENGINEERING (151 journals)                  1 2     

ACS Combinatorial Science     Full-text available via subscription   (Followers: 7)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 3)
Acta Polymerica     Hybrid Journal   (Followers: 6)
Additives for Polymers     Full-text available via subscription   (Followers: 18)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 4)
Advanced Chemical Engineering Research     Open Access   (Followers: 7)
Advances in Applied Ceramics     Partially Free   (Followers: 2)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 15)
Advances in Chemical Engineering and Science     Open Access   (Followers: 21)
Advances in Polymer Technology     Hybrid Journal   (Followers: 10)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 1)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 9)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 3)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 6)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
BMC Chemical Biology     Open Access   (Followers: 4)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 6)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 7)
Chemical and Process Engineering     Open Access   (Followers: 3)
Chemical and Process Engineering Research     Open Access   (Followers: 5)
Chemical Communications     Full-text available via subscription   (Followers: 27)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 24)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 9)
Chemical Engineering and Science     Open Access   (Followers: 2)
Chemical Engineering Communications     Hybrid Journal   (Followers: 10)
Chemical Engineering Journal     Hybrid Journal   (Followers: 16)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 15)
Chemical Engineering Science     Hybrid Journal   (Followers: 9)
Chemical Geology     Hybrid Journal   (Followers: 9)
Chemical Papers     Hybrid Journal   (Followers: 3)
Chemical Product and Process Modeling     Full-text available via subscription   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 251)
Chemical Society Reviews     Full-text available via subscription   (Followers: 26)
Chemical Technology     Open Access   (Followers: 4)
ChemInform     Hybrid Journal   (Followers: 3)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry of Materials     Full-text available via subscription   (Followers: 162)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 6)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 1)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 7)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 18)
Corrosion Reviews     Full-text available via subscription   (Followers: 4)
Crystal Research and Technology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Engineering     Open Access   (Followers: 2)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Focusing on Modern Food Industry     Open Access   (Followers: 3)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Geochemistry International     Hybrid Journal  
High Performance Polymers     Hybrid Journal  
Indian Chemical Engineer     Hybrid Journal   (Followers: 3)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 12)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 16)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 1)
International Journal of Chemical Engineering     Open Access   (Followers: 6)
International Journal of Chemical Reactor Engineering     Full-text available via subscription   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 3)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 2)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 3)
International Journal of Science and Engineering     Open Access   (Followers: 7)
International Journal of Waste Resources     Open Access   (Followers: 3)
ISRN Chemical Engineering     Open Access   (Followers: 4)
ISRN Polymer Science     Open Access   (Followers: 11)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 4)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 6)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 155)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 7)
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 6)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 1)
Journal of Chemical Engineering     Open Access   (Followers: 3)
Journal of Chemical Engineering and Materials Science     Open Access  
Journal of Chemical Science and Technology     Open Access   (Followers: 1)
Journal of Chemical Sciences     Partially Free   (Followers: 13)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 2)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 9)
Journal of Coatings     Open Access   (Followers: 2)
Journal of Crystallization Process and Technology     Open Access   (Followers: 5)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Fuels     Open Access  
Journal of Geochemical Exploration     Hybrid Journal  

        1 2     

Journal Cover Chemical Engineering Science
   [11 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0009-2509
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.033]   [H-I: 103]
  • Aerosol nucleation in a turbulent jet using Large Eddy Simulations
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): I. Pesmazoglou , A.M. Kempf , S. Navarro-Martinez
      This work presents a model for particle nucleation and transport in the context of Large Eddy Simulation. A turbulent Dibutyl-Phthalate-laden Nitrogen jet diffusing in atmospheric air is used for validation. The proposed nucleation model treats the process in a probabilistic manner where the frequency of events is determined from local equilibrium conditions. Two methodologies for the sub-grid influence on nucleation rates are implemented: the presumed β-PDF and the source expansion method. Good agreement is found with respect to the experimental results for particle concentrations. The differences between using mean and instantaneous values for the evaluation of the nucleation rate are shown. For the grid spacing used, the unresolved scales seem to have little influence on the calculated particle concentrations. It is concluded that the use of instantaneous nucleation rates is advantageous and therefore it is important to consider a particle coupling that allows for the full use of instantaneous values.


      PubDate: 2014-06-14T14:56:44Z
       
  • Effect of flow type, channel height, and viscosity on drop production from
           micro-pores
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Kathleen Feigl , Franz X. Tanner , Sebastian Holzapfel , Erich J. Windhab
      The formation and detachment of drops from micron-sized pores into shear flow fields is investigated using numerical simulations. The open source software OpenFOAM is used for the simulations. The numerical algorithm employs the finite volume method for solving the mass and momentum conservation equations with a volume-of-fluid approach for capturing the fluid–fluid interface. In addition, a contact model accounts for the interaction between the fluids and the walls of the channel and pore. After validating the numerical models and methods by comparison to experimental data, a parameter study is performed to investigate the effect of various geometrical, flow and fluid parameters on the characteristics of drop production, in particular, drop size. The effect of the type of imposed channel shear flow (pressure-driven or plane Couette), channel height and fluid viscosity is considered. It is found that, in one range of Reynolds and capillary numbers, the channel wall shear rate is a good indicator of drop sizes, regardless of imposed shear flow type, channel height or viscosity ratio. In this flow regime, a master drop size curve is produced for each viscosity ratio considered, with the curve being shifted lower for the higher viscous disperse phase. In another flow regime, when Reynolds numbers are very large relative to capillary numbers, the average shear rate in the channel was a better drop size indicator, although a different master curve was produced for each channel height.


      PubDate: 2014-06-14T14:56:44Z
       
  • Mathematical model for continuous and intermittent microwave-assisted
           extraction of bioactive compound from plant material: Extraction of
           β-carotene from carrot peels
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Nakarin Chumnanpaisont , Chalida Niamnuy , Sakamon Devahastin
      Microwave-assisted extraction (MAE) is a method that uses microwave energy to extract compounds from materials. Although many studies have recently been published on various aspects of MAE, an adequate model that can be used to predict the transport phenomena during MAE is still lacking. This study was therefore aimed to develop a mathematical model that can be used to describe the evolutions of temperature and concentration of an extract during both continuous and intermittent MAE; carrot peels were used as a test material and β-carotene concentration was modeled. The model consisting of the Maxwell’s, energy and species balance equations, along with appropriate initial and boundary conditions, was simulated using the finite element method via COMSOL MultiphysicsTM software. The model was validated by comparing the simulated results with the evolutions of the experimental temperature and β-carotene concentration. In general, the model was capable of predicting the evolutions of the temperature and β-carotene concentration quite adequately. In some cases, however, the temperature prediction was compromised due to the evaporation of solvent, which was not considered in the model. The empirical constants of the model were noted to depend on the specific absorbed microwave power and the sample-to-solvent ratio.


      PubDate: 2014-06-14T14:56:44Z
       
  • Molecular weight/branching distribution modeling of
           low-density-polyethylene accounting for topological scission and
           combination termination in continuous stirred tank reactor
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Nazila Yaghini , Piet D. Iedema
      We present a comprehensive model to predict the molecular weight distribution (MWD), 1 1 Molecular weight distribution. and branching distribution of low-density polyethylene (ldPE), 2 2 Low density polyethylene. for free radical polymerization system in a continuous stirred tank reactor (CSTR). 3 3 Continuous stirred tank reactor. The model accounts for branching, by branching moment or pseudo-distributions. The common free radical polymerization reactions including chain scission have been considered in the model. Non-linear or the so-called topological scission has been modeled using approximate fragment length distributions derived from scission, applied to branching topologies. To model the distributions, the Galerkin-FEM method based on the same principles as PREDICI® has been applied and implemented in MATLAB©. The fundamental numerical problem arising from topological scission has been solved. Thus, the model provides more accurate results, allowing a precise comparison to earlier results and to Monte Carlo simulations.


      PubDate: 2014-06-14T14:56:44Z
       
  • Multi-column chromatographic process development using simulated moving
           bed superstructure and simultaneous optimization – Model correction
           framework
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Balamurali Sreedhar , Yoshiaki Kawajiri
      In this work, we demonstrate an improved framework for simulated moving bed (SMB) chromatographic process development using a superstructure formulation. Various optimal column configurations and operations are obtained by solving a multi-objective optimization problem representing the superstructure by maximizing feed throughput and minimizing desorbent usage. In order to resolve the model mismatch with experimental data, here we utilize the simultaneous optimization – model correction (SOMC) method in which process optimization is carried out in tandem with model correction using data obtained from experimental evaluations. The potential of the superstructure–SOMC framework has been demonstrated by separating glucose and fructose using columns packed with a cation exchange resin with water as the mobile phase. The optimal operation modes found using the superstructure included standard SMB, three zone (3Z) operation, intermittent SMB (I-SMB) and a newly found outlet stream swing (OSS) – partial feed (PF) hybrid operation. All configurations were experimentally implemented using a Semba Octave ™ 100 Chromatography System.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:56:44Z
       
  • Geometric output tracking of nonlinear distributed parameter systems via
           adaptive model reduction
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Davood Babaei Pourkargar , Antonios Armaou
      We focus on the output tracking problem of distributed parameter systems (DPSs) which can be described by a set of nonlinear dissipative partial differential equations (PDEs). The infinite-dimensional modal representation of such systems in appropriate subspaces can be decomposed to finite-dimensional slow and probably unstable, and infinite-dimensional fast and stable subsystems. Taking advantage of this decomposition, adaptive model reduction techniques and specifically adaptive proper orthogonal decomposition (APOD) can be used for the recursive construction of locally accurate low dimensional reduced order models (ROMs). The proposed geometric APOD-based control structure is the combination of a nonlinear Luenberger-like geometric dynamic observer and a globally linearizing controller (GLC) designed for tracking the desired output. The proposed geometric control approach is successfully illustrated on the output tracking of target thermal dynamics for a catalytic reactor. Specifically, the geometric output tracking strategy is used to reduce the hot spot temperature and manage the thermal energy distribution through reactor length during process evolution with limited number of actuators and sensors.


      PubDate: 2014-06-14T14:56:44Z
       
  • Shape oscillations of a bubble or drop attached to a capillary tip
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Jiri Vejrazka , Lucie Vobecka , Sandra Orvalho , Maria Zednikova , Jaroslav Tihon
      The oscillation dynamics of bubbles and drops that are attached to the tip of a capillary are experimentally investigated to test the applicability of simplified linear analyses to real-world situations. The experiments are performed with 0.7–2.6mm air bubbles in pure water (without surfactants) and with 0.7–1.3mm drops of pure water. The bubbles or drops are excited by the vertical motion of the capillary. The consequent shape oscillations, which are recorded by a high-speed camera, are processed to determine the oscillation eigenmodes (their frequencies, shapes, and damping rates). If the bubbles or drops are sufficiently small to preserve the spherical static shapes, the measured characteristics of the eigenmodes will correspond to the analyses. If the bubble or drop size is sufficiently large to form a neck, the eigenmode frequency decreases and the shape oscillations will correspond to those of a free bubble. The reduction in eigenmode frequency is correlated with the ratio of the actual volume of the bubble to the detachment volume of the bubble.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Establishing photon absorption fields in a Photo-CREC Water II Reactor
           using a CREC-spectroradiometric probe
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): P.J. Valadés-Pelayo , Jesus Moreira del Rio , Pastor Solano-Flores , B. Serrano , H. de Lasa
      The scattering mode and the appropriate boundary conditions in a Photo-CREC Water II annular reactor are assessed from experimental data. These data are obtained by using a novel spectroradiometric probe (CREC-SP). This probe is designed to measure irradiation at different radial positions within the concentric channel. Radiation data obtained is analyzed using a calculated Monte Carlo radiation field inside the slurry photoreactor. The effect of the phase function and the boundary conditions, as relevant to the photoreactor walls, are determined. The MC method proposed by Valades-Pelayo et al. (2014, Chem. Eng. Sci., 107, 123–136) is modified in the present study to account for refraction, absorption and reflection at the probe surface. Lamp emission, refraction and reemission as well as wavelength-dependent absorption and scattering are accounted for. Regarding Degussa P25, a Henyey–Greenstein phase function with g=0.68±0.03 is needed. On this basis, a 3D LVRPA field is established. This approach also allows one to independently set boundary conditions, breaking, in this manner, their correlation with scattering parameters. As a result, this study establishes scattering phase functions and radiation absorption fields with improved accuracy. Clarification of these matters is of crucial importance for the design and scale-up of photocatalytic reactors.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Transient liquid holdup and drainage variations in gravity dominated
           non-porous and porous packed beds
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): I.M.S.K. Ilankoon , S.J. Neethling
      Transient liquid holdup effects are a crucial aspect of the behaviour of many unsaturated packed beds systems. This study examined both a model system consisting of spherical glass beads and a system containing slightly porous (about 5% water accessible porosity) rock particles. Experiments on different column heights show that the initial wetting front moving through the packed bed takes the form of a soliton or standing wave. The final drainage of the bed when the liquid addition is turned off shows slightly more complex behaviour than that of the initial wetting of the bed. It was demonstrated that if the behaviour of the liquid held around the particles is separated from that held within the particles, the same relatively simple model can be used to describe the drainage of both the model glass bead system and the slightly porous ore system despite the apparent differences in their behaviour, such as a much longer time to achieve the steady state, and a markedly different shape to the initial overall saturation versus time curve. This simple model assumed that for the liquid between the particles, gravity was the dominant force and that capillarity could be neglected. Neglecting capillarity probably accounts for the slight discrepancy between the experimental and simulated liquid holdup results in the porous ore system at intermediate drainage times.


      PubDate: 2014-06-14T14:56:44Z
       
  • Transient behavior of structured LaMnO3 catalyst during methane combustion
           at high pressure
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Gianluca Landi , Almerinda Di Benedetto , Paola S. Barbato , Gennaro Russo , Valeria Di Sarli
      In this work, the transient behavior of a perovskite-based monolith was investigated during catalytic combustion of methane at high pressure. The transient behavior of both a fully coated and a partially coated monolithic reactor was simulated. Numerical results have shown that the initial phase is mainly driven by heterogeneous reactions. The temperature increase due to the heat developed on the catalyst surface is responsible for the activation of the homogeneous reaction process that allows to get complete fuel consumption. The heat back-diffusion through the monolith walls is mainly responsible for the reaction front moving upstream. After anchoring of the reaction front at the monolith entrance, the dominant phenomenon is the warming up of the system that is ruled by the solid heat capacity. In the case of the partially coated reactor, ignition starts in the catalytic channels. Here, catalytic reactions activate homogeneous reactions. The heat generated is then transferred to the uncoated channels, thus allowing the on-set of homogeneous reactions and, consequently, the complete fuel consumption throughout the entire monolith.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Yeast cells as macropore bio-templates enhancing transport properties and
           conversions in coated catalyst layers for exhaust gas oxidation
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Marek Václavík , Michal Dudák , Vladimír Novák , Rostislav Medlín , František Štěpánek , Miloš Marek , Petr Kočí
      We propose an application of yeast cells as alternative, ecological and economical material for macropore templates that enhance transport properties and conversions in multiple coated catalyst layers. The grown baker׳s yeast cells exhibit a suitable, naturally uniform size, are cheap and readily removable from the layer upon calcination. Their application is demonstrated in Pt/γ-Al2O3 layers typically used in exhaust gas oxidation catalysts. The layers coated with and without yeast cells are compared by the means of porosimetry, cross-section SEM images and lab reactor tests for CO oxidation. Porous layer formation is simulated in 3D and multi-scale model is used to predict effective diffusivity and conversions of CO in the coatings. The model predictions agree well with lab reactor tests and clearly demonstrate improved transport properties and conversions in multiple layers configuration with additional macropores resulting from the yeast cell templates.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Membrane contactors for CO2 absorption – Application, modeling and
           mass transfer effects
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Karl Anders Hoff , Hallvard F. Svendsen
      Modeling of membrane contactors as absorber units requires a rigorous absorption model where the liquid phase is discretized in the radial direction. The current paper describes such a model for absorption of CO2 into aqueous alkanolamines. The model is validated with a large volume of experimental data for absorption of CO2 in membrane contactor units. A simplified version of the model is developed to enable fast design and scale up assessment of membrane contactor systems. Simulations are used to show the importance of introducing mixing points in order to avoid mass transfer limitations on the liquid side. This can be achieved by a novel design of the membrane fibers or by operating the contactors with liquid flow on the shell side and gas on the tube side.


      PubDate: 2014-06-14T14:56:44Z
       
  • Experimental spray zone characterization in top-spray fluidized bed
           granulation
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Matthias Börner , Thomas Hagemeier , Gunnar Ganzer , Mirko Peglow , Evangelos Tsotsas
      In fluidized bed granulation wetting and coating of particles depends on the atomization of a liquid binder agent. Droplet distribution and the subsequent micro-scale processes of droplet deposition on particle surfaces as well as drying of layers and liquid bonds between aggregated particles lead to a subdivision of the process space into two major compartments, a spray zone and a drying zone. By using a self-constructed, simple conductivity probe spray patterns inside the fluidized bed are located. The spatial demarcation of the compartments, which is dependent on the fluidization and spray conditions, is deduced. Particularly, nozzle height and nozzle gas flow rates influence the expansion of the spray zone and its intrusion into the bed. The presented results show by means of the particle residence time for the two considered compartments that an increased nozzle mass flow rate leads to significantly accelerated particle flow in the spray zone, and the fluidization velocity of the gas forces a faster particle re-circulation behavior in the entire fluidized bed. Consequently, process time for wetting and drying is reduced. By using a flat fluidized bed with rectangular cross section in combination with image-based acquisition techniques, particle velocities and solid volume fractions have been acquired. Comparing the results of particle circulation patterns with data obtained in cylindrical equipment shows that information can be transferred from the quasi-2D configuration to real 3D geometries.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Capturing CO2 from ambient air using a polyethyleneimine–silica
           adsorbent in fluidized beds
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Wenbin Zhang , Hao Liu , Chenggong Sun , Trevor C. Drage , Colin E. Snape
      Carbon Capture and Storage (CCS) uses a combination of technologies to capture, transport and store carbon dioxide (CO2) emissions from large point sources such as coal or natural gas-fired power plants. Capturing CO2 from ambient air has been considered as a carbon-negative technology to mitigate anthropogenic CO2 emissions in the air. The performance of a mesoporous silica-supported polyethyleneimine (PEI)–silica adsorbent for CO2 capture from ambient air has been evaluated in a laboratory-scale Bubbling Fluidized Bed (BFB) reactor. The air capture tests lasted for between 4 and 14 days using 1kg of the PEI–silica adsorbent in the BFB reactor. Despite the low CO2 concentration in ambient air, nearly 100% CO2 capture efficiency has been achieved with a relatively short gas–solid contact time of 7.5s. The equilibrium CO2 adsorption capacity for air capture was found to be as high as 7.3wt%, which is amongst the highest values reported to date. A conceptual design is completed to evaluate the technological and economic feasibility of using PEI–silica adsorbent to capture CO2 from ambient air at a large scale of capturing 1Mt-CO2 per year. The proposed novel “PEI-CFB air capture system” mainly comprises a Circulating Fluidized Bed (CFB) adsorber and a BFB desorber with a CO2 capture capacity of 40t-CO2/day. Large pressure drop is required to drive the air through the CFB adsorber and also to suspend and circulate the solid adsorbents within the loop, resulting in higher electricity demand than other reported air capture systems. However, the Temperature Swing Adsorption (TSA) technology adopted for the regeneration strategy in the separate BFB desorber has resulted in much smaller thermal energy requirement. The total energy required is 6.6GJ/t-CO2 which is comparable to other reference air capture systems. By projecting a future scenario where decarbonization of large point energy sources has been largely implemented by integration of CCS technologies, the operating cost under this scenario is estimated to be $108/t-CO2 captured and $152/t-CO2 avoided with an avoided fraction of 0.71. Further research on the proposed 40t-CO2/day ‘PEI-CFB Air Capture System’ is still needed which should include the evaluation of the capital costs and the experimental investigation of air capture using a laboratory-scale CFB system with the PEI–silica adsorbent.


      PubDate: 2014-06-14T14:56:44Z
       
  • Probabilistic latent variable regression model for process-quality
           monitoring
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Le Zhou , Junghui Chen , Zhihuan Song , Zhiqiang Ge , Aimin Miao
      Online monitoring of chemical industrial processes is crucial to the healthy assessment of the operation status. In recent years, the monitoring schemes based on probabilistic principal component analysis (PPCA) models have been developed and applied in industries. PPCA is an effective tool for detecting the variations of process variables but does not utilize quality variables. In this paper, the probabilistic latent variables regression (PLVR) is proposed. It extends the monitoring framework of PPCA by including the quality information for monitoring performance improvement. The PLVR model calibrated by the expectation-maximization algorithm is systematically developed. In PLVR, the effective latent variables, which are more sensitive to the variations of quality variables by monitoring the input subspace, can be determined through the covariance with information from the process and the quality variables. With this novel PLVR model, new statistics for PLVR is also presented for easy tracking of the operating process. It can also monitor the occurrence of the upsets of product qualities. Finally, the advantages of the proposed method over PPCA are presented through a case study of the Tennessee Eastman benchmark process characterized by fault sources.


      PubDate: 2014-06-14T14:56:44Z
       
  • A model based approach for identifying robust operating conditions for
           industrial chromatography with process variability
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Edward J. Close , Jeffrey R. Salm , Daniel G. Bracewell , Eva Sorensen
      A model based approach has been developed and used to identify robust operating conditions for an industrial hydrophobic interaction chromatography where resin lot variability, combined with feed stream variability, was resulting in serious performance issues during the purification of a multi component therapeutic protein from crude feed material. An equilibrium dispersive model was formulated which successfully predicted the key product critical quality attribute during validation studies. The model was then used to identify operating parameter ranges that assured product quality despite the process variability. Probabilistic design spaces were generated using stochastic simulations that showed the probability that each resin lot would meet product quality specifications, over a range of possible operating conditions, accounting for the historical variability experienced in the load material composition and concentration. No operating condition was found with normal process variability where quality assurance remained >0.95 for resins that gave the highest and lowest product recoveries during process development. The lowest risk of batch failure found was 16%, and operating conditions were not robust. We then extended the stochastic methodology used to generate probabilistic design spaces, to identify the level of control required on the load material composition and concentration to bring process robustness to an acceptable level, which is not possible using DOE experimental methods due to the impractical amount of resources that would be required. Although reducing inlet variability resulted in an increase in the assurance of product quality, the results indicated that changing operating conditions according to which resin lot is in use is the favorable option.


      PubDate: 2014-06-14T14:56:44Z
       
  • Applicability of a Taylor–Couette device to characterization of
           turbulent drag reduction in a pipeline
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Dmitry Eskin
      A model of turbulent drag reduction in a pipe is developed. The model employs a well-known two layer representation of the boundary layer structure. An approach of Yang and Dou (2010) to model the drag reduction effect, as a phenomenon caused by a non-Newtonian rheology of a viscous sublayer flow, is employed. The modified Prandtl–Karman equation for calculation of the friction factor in a pipe flow of a dilute polymer solution is derived. This equation contains the only empirical parameter that is a function of a polymer type and concentration. The results obtained using the model developed are in a good agreement with those calculated by the Yang and Dou (2010) model, verified against experimental data. An engineering model of a turbulent dilute polymer solution flow in a Couette device is also developed. The same approach to modeling drag reduction as that in a pipe flow is applied. The model allows to compute the dimensionless torque applied to the Couette device rotor as a function of the rotation speed for a given polymer type and concentration. Thus, the empirical parameter, characterizing drag reduction by using a certain polymer additive, can be identified from laboratory Couette device experiments requiring small fluid amounts, and then applied to forecast drag reduction in industrial-scale pipeline flows.


      PubDate: 2014-06-14T14:56:44Z
       
  • Flow and mixing analysis of non-Newtonian fluids in straight and
           serpentine microchannels
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Arshad Afzal , Kwang-Yong Kim
      Numerical simulations were carried out to investigate the flow dynamics and mixing behavior in T-shaped and serpentine microchannels with non-Newtonian working fluids using shear-dependent viscosity models. As an illustrative case study, the microfluidic transport of blood was considered. The Carreau–Yasuda and Casson non-Newtonian blood viscosity models were used to capture the non-Newtonian characteristics. Steady Navier–Stokes equations with a diffusion-convection model for species concentration were solved in flow and mixing analyses. Under similar operating conditions, flow dynamics and mixing were compared between the working fluids: water (a Newtonian fluid), and blood using the Carreau–Yasuda non-Newtonian model. For a mass flow rate of m ̇ < 10 − 2 k g / h , the mixing performances of both the fluids were found to be nearly equivalent, and decreased with flow rate. With increased flow rate, the mixing with water was significantly improved. However, a negligible change in mixing performance was observed using the Carreau–Yasuda model for blood. Also, the pumping power needed was considerably higher for the blood sample (~1bar) than for water (~0.40bar) at the same flow rate. The mixing behavior with the Carreau–Yasuda blood model was compared for T-shaped and serpentine channels over a fixed mixing length. The serpentine channel showed better mixing performance over the flow rate range considered.


      PubDate: 2014-06-14T14:56:44Z
       
  • Multi-stage energy analysis of steam explosion process
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Wenjie Sui , Hongzhang Chen
      Owing to the deficiency of investigating steam explosion on energy utilization, in this study, we analyze the heat transfer mechanism and energy consumption of steam explosion process. Based on years of research, we propose that energy consumption of steam explosion not only involves holding pressure and instantaneous decompression stages but also the upward stage of pressure. On this basis, a multi-stage heat transfer model of steam explosion process integrating technical features is established. Results reveal the significance of pressure boost stage which contributes the vast majority of total energy consumption. The amount of steam consumption per unit mass of dry materials m′ is presented to quantitatively evaluate the energy consumption under various factors, in which initial moisture content is considered as the most important factor. Several rational operational strategies for improving energy efficiency are proposed including controlling low moisture content of materials (<40%), adopting low-temperature and long-time parameters as well as properly reducing particle size. Such representations not only contribute to utilization of energy but considerably facilitate optimization, simulation, design and control of steam explosion process, consequently improving the large-scale deployment of steam explosion technology.


      PubDate: 2014-06-14T14:56:44Z
       
  • Numerical simulation of carbon dioxide (CO2) absorption and interfacial
           mass transfer across vertically wavy falling film
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Jianguang Hu , Xiaogang Yang , Jianguo Yu , Gance Dai
      The process of CO2 absorption in many currently used chemical devices can be typically characterised and analysed by mass transfer across a thin falling film gas–liquid interface. There is still a lack of general predictability of the transfer quantity based on the basic hydrodynamic parameters involved in such mass transfer processes, and certain important phenomena associated with the transfer still remain unexplained. A novel concept that utilises the correlation between the vorticity neighbouring the falling film gas–liquid interface and the gas concentration to characterise CO2 absorption mass transfer by the falling film is proposed in this work. Numerical simulations using a volume of fluid (VOF) approach were performed for a vertical falling film arrangement. The wave hydrodynamics and the associated mass transfer are discussed, and the numerical results are compared with the existing experimental empirical relationships. In particular, the mass transfer across the falling film interface is interpreted as the passive scalar entrapment and entrainment by the interfacial vortices. The numerical simulation clearly indicates that two types of vortices exist: wall-bounded vortices associated with primary shear in the falling film and interfacial vortices associated with weaker shear in the vicinity of the interface. The numerical simulation reveals that mass transfer across the falling film is highly correlated with the interfacial vorticity Ω i , thus indicating the use of c Ω i ¯ is able to characterise the mass transfer across the falling film gas–liquid interface.


      PubDate: 2014-06-14T14:56:44Z
       
  • On the kinetics of the isomerization of glucose to fructose using Sn-Beta
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Nafiseh Rajabbeigi , Ana I. Torres , Christopher M. Lew , Bahman Elyassi , Limin Ren , Zhuopeng Wang , Hong Je Cho , Wei Fan , Prodromos Daoutidis , Michael Tsapatsis
      Process design and techno-economic evaluation of glucose isomerization on Sn-Beta require reliable catalytic reaction rate expressions and kinetic constants. Here, the isomerization of sugars (glucose, fructose and mannose) in water using Sn-Beta is investigated at various temperatures ranging from 70 to 130°C. It is shown that the catalyst deactivates during the course of the reaction. A phenomenological model that describes the isomerization reaction in the presence of deactivation is developed and the corresponding kinetic constants are estimated from experimental data.


      PubDate: 2014-06-14T14:56:44Z
       
  • Surfactant-mediated settleability and dewaterability of activated sludge
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Long-Fei Wang , Ling-Ling Wang , Wen-Wei Li , Dong-Qin He , Hong Jiang , Xiao-Dong Ye , Hai-Ping Yuan , Nan-Wen Zhu , Han-Qing Yu
      The activated sludge process is widely used for wastewater treatment, and the settleability and dewaterability of activated sludge are crucial to the operation of wastewater treatment plants. In this study the surfactant-mediated settleability and dewaterability of activated sludge were investigated. It is found that dose of anionic surfactant sodium dodecyl sulfate (SDS) caused substantial release of extracellular polymer substances (EPS), especially proteins, from sludge. Laser light scattering (LLS) results reveal that the released EPS became stretched and more expanded when the SDS dosage was increased. The sludge dewaterability was significantly deteriorated at a dosage of 2.084g/L SDS, and meanwhile the capillary suction time (CST) and specific resistance of filtration (SRF) increased by 6.3 and 5.1 times, respectively, than the raw sludge. The correlations between the EPS contents and the sludge properties, i.e., CST, SRF, moisture content of filter-cake and sludge volume index, were evaluated and the significant roles of proteins in governing the EPS properties as well as the settleability and dewaterability of sludge were further confirmed. This study elucidates how the settleability and dewaterability of activated sludge were affected by surfactants via changing the properties and structure of the released EPS from sludge.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Agro-industrial acidic oil as a renewable feedstock for biodiesel
           production using (1R)-(–)-camphor-10-sulfonic acid
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Adeeb Hayyan , Mohd Ali Hashim , Maan Hayyan
      A mixture of low grade industrial oils such as acidic crude palm oil (ACPO) and sludge palm oil (SPO) was used for biodiesel production. A novel organic acid, (1R)-(–)-camphor-10-sulfonic acid (10-CSA), was introduced as a catalyst for esterification reaction. 10-CSA shows high activity as a catalyst in the reduction of free fatty acid (FFA) and high conversion of fatty acid methyl ester (FAME). The effects of reaction temperature, reaction time and molar ratio on FFA reduction and FAME conversion were studied. The FFA content was reduced from 8% to less than 1% under optimum conditions. The final product (biodiesel fuel) produced from treated oils (ACPO and SPO) meets international biodiesel standards. This is the first time 10-CSA has been introduced as a catalyst for esterification reaction. This catalyst can treat a wide range of acidic raw materials for biodiesel production. 10-CSA is a promising catalyst and can be used for various chemical reactions.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Characterization of the particle–wall frictional forces in pseudo-2D
           fluidized beds using DEM
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): F. Hernández-Jiménez , T. Li , E. Cano-Pleite , W. Rogers , A. Acosta-Iborra
      In this work a numerical study of a pseudo-2D gas fluidized bed is carried out using the MFIX-DEM code with a twofold aim. The first aim is to check whether the DEM code reproduces the overall experimental value of the frictional force of the walls on the particles in the pseudo-2D bed in bubbling regime, previously measured by Hernández-Jiménez et al. (2013) by means of a global force balance in the bed. The second aim of this work is to perform a local study of the wall–particle frictional forces, using the results of the DEM simulations. The results showed that the force balance proposed by Hernández-Jiménez et al. (2013) is consistent with the DEM simulations, corroborating that the particle–wall overall force can be considered equal to the velocity of the centre of mass times a global particle–wall interaction coefficient, c. Besides, it was found that the most probable value of the local coefficient c in the DEM simulations is similar to the global value experimentally obtained. As expected, the DEM results showed that this particle–wall interaction coefficient, c, increases with the particle–wall friction coefficient. Coincidence between simulations and experiments is maximum if an angle of internal friction very close to 30° is considered in the DEM particle–wall interaction.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:56:44Z
       
  • Comparison of solids suspension criteria based on electrical impedance
           tomography and visual measurements
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Petri Tervasmäki , Jari Tiihonen , Heikki Ojamo
      Different approaches have been adopted to quantify the performance of stirred vessels in suspending sinking solids into liquid phase. In this study we used electrical impedance tomography (EIT) to estimate the solids distribution in a lab-scale stirred vessel with a diameter of 362mm. Also visual measurements were performed to determine the cloud height and just suspended impeller speed. Quartz sand with a density of 2650kg/m3 was employed as the solid phase with different particle size fractions from 50 to 180µm and solids volume fractions of 7.5% and 15%. The effect of impeller type was studied by using two axial flow impellers, a pitched blade turbine and a hydrofoil impeller. Two different states—partial and homogeneous suspensions—were defined from the EIT data in addition to visual measurement of complete off-bottom suspension and cloud height. Partial suspension was determined from the EIT data, and it was reached at relatively low agitation rates. Visual measurements and data from the literature also support this observation, and EIT was proved to be a suitable method to quantify a repeatable partial suspension criterion. Complete off-bottom suspension was measured visually by determining the agitation rate at which there were no stationary solid particles at the vessel bottom for longer than 2s. However, the applicability of this widely used criterion was questioned in the case of dense suspensions of small particles. Homogeneous suspension was estimated from the EIT data, and it was reached by approximately doubling the impeller revolution rate from the partial suspension criterion. The hydrofoil impeller reached all states of suspension with lower power consumption compared to the pitched blade turbine.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Reaction mechanism for glycerol dehydration in the gas phase over a solid
           acid catalyst determined with on-line gas chromatography
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Isabelle Martinuzzi , Yassine Azizi , Jean-François Devaux , Serge Tretjak , Orfan Zahraa , Jean-Pierre Leclerc
      Gas phase glycerol dehydration to form acrolein over a solid acid catalyst was studied to understand the formation of by-products and to establish a detailed reaction mechanism. The experiments were conducted in an isothermal fixed bed reactor operated under various conditions (temperature, space-time velocity, concentration). From a methodological point of view, many secondary products of the reaction were passed separately over the catalyst to understand the different pathways of glycerol dehydration. Our scientific contribution to the analytical method is that all of the products were analyzed simultaneously using a multivalve on-line gas chromatograph equipped with a flame ionization detector and a thermal conductivity detector. Two products were quantified using high performance liquid chromatography, and the unknown products (2-methyl 2-cyclopenten-1-one, 3-methyl 2-cyclopenten-1-one and 2,3-butanedione) were identified by gas chromatography–mass spectrometry. Several new compounds were found. Based on the determined products, a detailed reaction mechanism was proposed.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • The impact of Marangoni convection on fluid dynamics and mass transfer at
           deformable single rising droplets – A numerical study
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Roland F. Engberg , Mirco Wegener , Eugeny Y. Kenig
      In this paper, fluid dynamics and mass transfer of single droplets rising in a quiescent ambient liquid are considered. For the first time, full three-dimensional simulations of a deformable droplet dominated by Marangoni convection induced by concentration gradients were performed. A level set based code accounting for the mutual coupling of mass and momentum transfer was developed and implemented in the open-source computational fluid dynamics (CFD) package OpenFOAM ® . The liquid/liquid extraction test system toluene/acetone/water was investigated, and numerical results were compared with experimental data from the literature. The code captures and reproduces the characteristic experimental results: the two-step acceleration behaviour, the temporary reduction of the drop rise velocity, and the enhancement of mass transfer depending on the initial solute concentration. The lateral break-out in the drop path at the instant of reacceleration has only been observed experimentally so far. Our simulations reproduce this phenomenon, confirming the existence of pressure gradients across the droplet. Furthermore, our results reveal that the break-out effect is governed by rear vortex detachment.
      Graphical abstract image Highlights

      PubDate: 2014-06-14T14:56:44Z
       
  • Investigation of flow hydrodynamics and regime transition in a
           gas–solids fluidized bed with different riser diameters
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Guizhi Qiu , Jiamin Ye , Haigang Wang , Wuqiang Yang
      It is important to understand the flow hydrodynamics behavior of a circulating fluidized bed (CFB) reactor for efficient operation. The objective of this research is to identify and characterize the flow regimes in a fluidized bed with different riser diameters. For this purpose, electrical capacitance tomography (ECT) combined with pressure measurement has been used to investigate the flow characteristics and flow regime transitions. Experiment was carried out in a cold gas–solids fluidized bed to investigate the flow regimes and the transition velocities. Three risers of different diameter, 10, 12 and 15cm, are designed and used for comparison. A twin-plane ECT sensor and a differential pressure transducer are used to obtain the solids volume fraction and differential pressure in the bottom region. Different flow regimes including bubbling, slugging and turbulent flow regime were formed with two distinct transition velocities. The flow characteristics are investigated in terms of solids volume fraction, bubble diameter and bubble rising velocity. The transition velocities are compared based on the ratio of the static bed height to bed diameter (H st /D) and the measured position (i.e. the axial position and radial position).
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Ligament-type liquid disintegration by a spinning wheel
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Benjamin Bizjan , Brane Širok , Marko Hočevar , Alen Orbanić
      In this paper, liquid disintegration by a spinning wheel was investigated experimentally. The mechanism of ligament formation on a spinning wheel was studied using photographs taken by a high-speed camera. Three different liquids with Newtonian properties were used at various flow rates and the wheel rotational speed was varied in a wide range. The atomization process was found to be significantly different from the spinning disc and cups atomization due to the highly non-uniform circumferential ligament distribution and the absence of the direct drop formation mode. Nevertheless, the dependence of ligament number and diameter on the input process parameters is similar as with other types of centrifugal atomizers due to the same underlying hydrodynamic instabilities.


      PubDate: 2014-06-14T14:56:44Z
       
  • Continuous purification of active pharmaceutical ingredients using
           multistage organic solvent nanofiltration membrane cascade
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Ludmila Peeva , Joao da Silva Burgal , Irina Valtcheva , Andrew G. Livingston
      Downstream processing accounts for a large fraction of the production costs in pharmaceutical manufacturing. Organic solvent nanofiltration performed in a membrane cascade offers an interesting possibility for a continuous downstream processing unit operation. This work demonstrates continuous purification of Active Pharmaceutical Ingredient (API) Roxithromycin from potential Genotoxic Impurity (GTI) 4-dimethylaminopyridine (DMAP) in a simple and efficient two stage membrane cascade. Cascade performance is initially evaluated via mathematical simulations, and then validated experimentally. We demonstrated that by careful selection of operating parameters, high purity of the API >99% could be achieved from feed stream purity of 78%. The continuous cascade could be easily coupled with an adsorption column, utilising an inexpensive non-selective adsorbent such as charcoal, as a solvent recovery stage. The combined continuous process generates orders of magnitude less waste than a batch diafiltration which makes it an attractive alternative purification process for pharmaceutical industry.


      PubDate: 2014-06-14T14:56:44Z
       
  • Multi-scale flow simulation of automotive catalytic converters
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Cansu Ozhan , Daniel Fuster , Patrick Da Costa
      The flow distribution within the automotive catalytic converter is an important controlling factor on the overall conversion efficiency. Capturing the flow features minimizing the computational cost is the first important step towards the solution of the complex full engineering problem. In this work we present a novel approach that combines physical and numerical multi-resolution techniques in order to correctly capture the flow features inside an automotive catalytic converter. While Adaptive Mesh Refinement techniques are optimized in order to minimize the computational effort in the divergent region, a novel subgrid model is developed to describe the flow inside the catalytic substrate placed between the convergent and divergent regions. The proposed Adaptive Mesh Refinement methods are tested for two test cases representative of the flow features found in the divergent region of a catalytic converter. The performance of the new subgrid model is validated against the non-uniformity index and the radial velocity profile data obtained by Benjamin et al. (2002). The effective coupling of AMR techniques and the subgrid model significantly reduces the error of the numerical predictions to 5–15% in conditions where the full simulation of the problem is out of current computational capabilities.


      PubDate: 2014-06-14T14:56:44Z
       
  • Measurements of hydrate film fracture under conditions simulating the rise
           of hydrated gas bubbles in deep water
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Sheng-Li Li , Chang-Yu Sun , Guang-Jin Chen , Zhi-Yun Li , Qing-Lan Ma , Lan-Ying Yang , Amadeu K. Sum
      In view of gas hydrate formation in the containment of deep water oil/gas blowout, the evolution of methane hydrate films on gas bubbles rising naturally in deep water was simulated and observed by visual microscopy. The results reveal that hydrate films on gas bubbles formed at conditions corresponding to deeper depths (higher pressure) rose intact for longer distances and showed more pronounced fractures on the film. Secondary hydrate growth happened along the cracks of the hydrate film as the hydrated bubble rose upward. The fractured hydrate films were more likely to close with secondary growth when formed at subcoolings higher than 3.0K. The strength of methane hydrate film formed on the surface of a suspended gas bubble was examined by rapidly decreasing the external pressure of the hydrate film soon after its formation. The maximum tension that the hydrate film could withstand without fracturing as well as the tensile strength were evaluated for hydrate films formed at 277.2K and different subcoolings. It was found that the tensile strength of hydrate film increased with increasing subcooling at the formation conditions.


      PubDate: 2014-06-14T14:56:44Z
       
  • Risk-based operational performance analysis using loss functions
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Seyed Javad Hashemi , Salim Ahmed , Faisal I. Khan
      This paper proposes a risk-based process performance assessment methodology using loss functions. The proposed method helps to overcome the existing challenges in assessing impacts of deviations of process variables on safety and economy of a process operation. The inverted Beta loss function is used to incorporate the effects of process deviations on the safety and quality losses. The demand rate adjustment factor is used to model the effect of process deviations on the failure probability of safety systems. The probability of a failed process state due to abnormal events is continuously updated based on the current value of the characteristic variables. The use of the loss function approach in combination with probability updating provides a continuously revised risk estimation. Such a real-time risk profile provides a leading performance indicator for decision-making at an operational level. As an example, a temperature surge in a continuous stirred tank reactor is used to demonstrate the efficacy of the proposed methodology.


      PubDate: 2014-06-14T14:56:44Z
       
  • Numerical modelling of breakage and adhesion of loose fine-particle
           agglomerates
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Duy Nguyen , Anders Rasmuson , Kyrre Thalberg , Ingela Niklasson Bjo¨rn
      In this study, discrete element method (DEM) simulations are used to examine the breakage and capturing behaviour of loose fine-particle agglomerates on impact with a target particle. The model system is an agglomerate composed of 5µm fine particles and a 200µm target particle. The cohesion between fine particles was modelled using the Johnson, Kendall and Roberts (JKR) theory. In contrast to the breakage of hard agglomerates which break in large fragments, as commonly investigated, loose agglomerates break in finer fragments. Impact velocity was found to be a significant parameter not only for the adhesion strength but also for the structure of the particles captured on the target. The capture ratio of the agglomerate as well as the thickness of the particle layer covering the target decreases with increasing impact velocity. High impact velocity results in finer fragments attached to the target with greater tensile strength due to the re-structuring mechanism that occurs during impact. Accordingly, impact velocity is one of the critical parameters governing the structure resulting after collision. However, the effect of material properties, e.g. surface energy, material hardness and plasticity, on adhesion behaviour should be investigated to obtain a full picture of the breakage-adhesion regime map.


      PubDate: 2014-06-14T14:56:44Z
       
  • Robust multicomponent IR-to-concentration model regression
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Daniel J. Griffin , Martha A. Grover , Yoshiaki Kawajiri , Ronald W. Rousseau
      Infrared absorbance measurements can be made in situ and rapidly. Calibrating these measurements to give solution compositions can therefore yield a powerful tool for process monitoring and control. In many applications it is desirable to monitor the concentrations of multiple components in a complex solution under varying process conditions (which may introduce error in the absorbance measurements). Establishing a model that is capable of accurately predicting the concentrations of multiple components from infrared absorbance measurements that may be corrupted by error requires a carefully designed calibration procedure—a key part of which is model regression. In this article, a number of commonly used multivariate regression techniques are examined in the context of developing a model for simultaneously predicting the concentrations of four solutes from noisy infrared absorbance measurements. In addition, a tailored support vector regression algorithm—designed to produce a robust (measurement error-insensitive) calibration model—is developed, tested, and compared against these established regression algorithms.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Partial oxidation of methane over a ruthenium phthalocyanine catalyst
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Yuan Zhu , Robert Barat
      The partial oxidation of He-diluted CH4 with O2 has been studied in a laboratory flow reactor packed with fragmented pellets of zeolite-encaged Ru phthalocyanine catalyst. Gas compositions (CH4, O2, CO, CO2, and H2) were determined by on-line GC/TCD. Absolute system pressure was maintained at 445kPa. Most experiments were performed at a constant gas space velocity=0.717/s. Data were obtained over wide ranges of temperature (523–648K) and CH4/O2 feed molar ratio (0.5–6.5). Observed conversion of CH4 increased with temperature. Product selectivities of H2 and CO increased, while that of CO2 decreased, with increasing temperature and feed CH4/O2. Based on data analysis with an integral plug flow packed bed reactor model, the power law kinetic rate for CH4 conversion was observed to be first order in each of O2 and CH4. A non-linear Arrhenius plot of the global rate constants, together with a Mears correlation analysis, suggests that an external mass transfer resistance becomes active above 573K in this system.


      PubDate: 2014-06-14T14:56:44Z
       
  • Forces acting on a single introduced particle in a solid–liquid
           fluidised bed
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Zhengbiao Peng , Swapnil V. Ghatage , Elham Doroodchi , Jyeshtharaj B. Joshi , Geoffrey M. Evans , Behdad Moghtaderi
      In a liquid fluidised bed system, the motion of each phase is governed by fluid–particle and particle–particle interactions. The particle–particle collisions can significantly affect the motion of individual particles and hence the solid–liquid two phase flow characteristics. In the current work, computational fluid dynamics–discrete element method (CFD–DEM) simulations of a dense foreign particle introduced in a monodispersed solid–liquid fluidised bed (SLFB) have been carried out. The fluidisation hydrodynamics of SLFB, settling behaviour of the foreign particle, fluid–particle interactions, and particle–particle collision behaviour have been investigated. Experiments including particle classification velocity measurements and fluid turbulence characterisation by particle image velocimetry (PIV) were conducted for the validation of prediction results. Compared to those predicted by empirical correlations, the particle classification velocity predicted by CFD–DEM provided the best agreement with the experimental data (less than 10% deviation). The particle collision frequency increased monotonically with the solid fraction. The dimensionless collision frequency obtained by CFD–DEM excellently fit the data line predicted by the kinetic theory for granular flow (KTGF). The particle collision frequency increased with the particle size ratio (d P2/d P1) and became independent of the foreign particle size for high solid fractions when the fluidised particle size was kept constant. The magnitude of collision force was 10–50 times greater than that of gravitational force and maximally 9 times greater than that of drag force. A correlation describing the collision force as a function of bed voidage was developed for St p>65 and d P2/d P1≤2. A maximum deviation of less than 20% was obtained when the correlation was used for the prediction of particle collision force.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Influence of the emulsion formulation in premix emulsification using
           packed beds
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Akmal Nazir , Remko Marcel Boom , Karin Schroën
      Premix emulsification was investigated using packed beds consisting of micron-sized glass beads, a system that avoids fouling issues, unlike traditional premix membrane emulsification. The effects of emulsion formulation were investigated, most notably the viscosity and the surfactant. The droplet size was reduced by increased shear stress in the emulsion. This was stronger at low viscosity ratios than at high ratios. As expected the flux was proportional to the overall emulsion viscosity, and emulsions with small droplet size (Sauter mean droplet diameter <5μm) could still be produced at up to 60% of dispersed phase provided that sufficient surfactant was available. More uniform emulsions (span≈0.75) were produced with Tween-20 (nonionic) and SDS (anionic) as surfactants than with CTAB (a cationic surfactant), possibly due to a combination of a low equilibrium interfacial tension and electrostatic attractions with the glass surface. Scaling relations were proposed taking into account all investigated product properties that can describe the droplet size successfully.


      PubDate: 2014-06-14T14:56:44Z
       
  • Foaming and gas dispersion properties of non-ionic surfactants in the
           presence of an inorganic electrolyte
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): G. Bournival , Z. Du , S. Ata , G.J. Jameson
      Foams represent an important area of research due to their relevance in many industrial processes. Where there are geographical constraints, which can limit access to fresh water, there is an economic incentive in using recycled water, bore water and even seawater for industrial purposes. This creates a growing interest in determining the effect of inorganic electrolytes on foaming and gas dispersion properties of non-ionic surfactant solutions. The present study compares the foaming and gas dispersion properties of the non-ionic surfactants 1-pentanol, tri(propylene glycol) methyl ether, and poly(propylene glycol) 425. For all surfactants, the stabilisation mechanism was influenced by the concentration of surfactant and the presence of salt with PPG being affected to a lesser extent. Sodium chloride was observed to have a detrimental effect on foaming at higher surfactant concentrations but improved foaming at low surfactant concentrations. At low surfactant concentrations, the addition of salt improved foaminess by dampening the hydrophobic force. An increase in gas holdup with increasing surfactant concentration was observed and was attributed to a decrease in bubble size. For poly(propylene glycol) an initial decrease in gas holdup was observed at very low concentrations. Salt mainly affected gas dispersion properties at a higher concentration.


      PubDate: 2014-06-14T14:56:44Z
       
  • Modeling a continuous flow ultraviolet Light Emitting Diode reactor using
           computational fluid dynamics
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Richard M. Jenny , Otto D. Simmons III , Max Shatalov , Joel J. Ducoste
      The use of ultraviolet (UV) light for water treatment disinfection has become increasingly popular due to its ability to inactivate chlorine-resistant microorganisms without the production of known disinfection by-products. Currently, mercury-based lamps are the most commonly used UV disinfection source; however, these lamps are toxic if broken during installation or by foreign object strike during normal operation. In addition, disposal of degraded, hazardous mercury lamps can be challenging in rural and developing countries for point-of-use (POU) drinking water disinfection applications. UV Light Emitting Diodes (LEDs) offer an alternative, non-toxic UV source that will provide design flexibility due to their small size, longer operating life, and fewer auxiliary electronics than traditional mercury-based lamps. Modeling of UV reactor performance has been a significant approach to the engineering of UV reactors in drinking water treatment. Yet, no research has been performed on the experimental and modeling of a continuous flow UV-LED reactor. A research study was performed to validate a numerical computational fluid dynamics (CFD) model of a continuous flow UV-LED water disinfection process. Reactor validation consisted of the following: (1) hydraulic analysis using tracer tests, (2) characterization of the average light distribution using chemical actinometry, and (3) microbial dose–response and inactivation using biodosimetry. Results showed good agreement between numerical simulations and experimental testing. Accuracy of fluid velocity profile increased as flow rate increased from 109mL/min to 190mL/min, whereas chemical actinometry saw better agreement at the low flow rate. Biodosimetry testing was compared only at the low flow rate and saw good agreement for log inactivation of bacteriophage Qβ and MS-2 at 92% and 80% UV transmittance (UVT). The results from this research can potentially be used for the design of alternative point-of-use drinking water disinfection reactors in developing countries using UV LEDs.


      PubDate: 2014-06-14T14:56:44Z
       
  • Lattice-Boltzmann simulation of fluid flow through packed beds of spheres:
           Effect of particle size distribution
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): L.W. Rong , K.J. Dong , A.B. Yu
      Fluid flowing through packed beds of multi-sized spheres is studied by a parallel lattice-Boltzmann (LB) model. The packed beds are generated by means of the discrete element method. First, the LB model is used to study the effects of size ratio and volume fraction on the fluid flow and quantify the drag forces on binary mixtures of particles. Typical flow behaviours are identified in relation to pore geometries. The results suggest that the polydispersity in particle size enhances local structure heterogeneity and flow non-uniformity, resulting in distributed fluid–particle interaction forces. Then, based on the simulated data, a new equation is formulated to calculate the mean individual drag force. The equation is extended to multicomponent mixtures of particles. The results show that the new equation is more accurate and reliable than those in the literature, and can be generally used in the modelling of particle–fluid flows.


      PubDate: 2014-06-14T14:56:44Z
       
  • Nucleation of cyclopentane hydrate by ice studied by morphology and
           rheology
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Genti Zylyftari , Amit Ahuja , Jeffrey F. Morris
      Results from an experimental study of the effects of heterogeneous nucleation of cyclopentane hydrate by ice on the morphological properties of hydrate formed on a single aqueous drop immersed in cyclopentane and the rheological properties of density-matched 40% (v/v) aqueous fraction hydrate-forming emulsions are reported. Experimental observations indicate that the ice-oil-aqueous phase contact line is the hydrate heterogeneous nucleation site. A novel observation showing the critical nature of heterogeneous nucleation is reported: the heterogeneous nucleation of hydrate from ice is found to be qualitatively controlled by the temperature ramp rate in the experiment. Apparently, a low temperature ramp rate results in more heterogeneous nucleation sites for hydrate, and thus a higher surface area crystal structure than a rapid heating rate. The viscosity of a metastable hydrate-forming emulsion evolves rapidly when the emulsion is seeded with ice, although more slowly than when seeded with the hydrate itself. The critical time, defined as the time (measured from the seeding time) when an abrupt jump in viscosity is observed, decreases with higher subcooling; for hydrate-seeded emulsions this time varies from about 15min to three hours as the subcooling is decreased from 7.3°C to 4.3°C; the slower growth with ice relative to hydrate seeding is seen in the larger critical time for ice seeding, as the critical time for ice seeding lags approximately one hour when compared to hydrate-seeded hydrate-forming emulsions, over this same range of subcoolings.


      PubDate: 2014-06-14T14:56:44Z
       
  • Gas mixing study in freely bubbling and turbulent gas–solid
           fluidized beds with a novel infrared technique coupled with digital image
           analysis
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): T.Y.N. Dang , F. Gallucci , M. van Sint Annaland
      A novel experimental technique using a high speed Infrared (IR) camera combined with an improved Digital Image Analysis (DIA) method for non-invasive concentration measurement with high spatial and temporal resolution has recently been developed by Dang et al. (2013). This paper reports the extension of the IR technique to freely bubbling and turbulent fluidization regimes to investigate and quantify lateral gas mixing characteristics in gas–solid fluidized beds. The mechanism of lateral gas mixing in the bubbling regime studied with the novel technique is in good agreement with values reported in the literature. The experimental results, interpreted with a plug flow model with superimposed dispersion for a homogeneous flow, show that the lateral gas mixing coefficient first increases with the increase of superficial gas velocities from the bubbling to the turbulent flow regime and then decreases for even higher velocities, which is consistent with earlier literature studies. The dependency of the lateral gas mixing coefficient on the Reynolds number using Amos׳ correlation (Amos and Mineo, 1993) has shown large discrepancies at low gas velocities (where the equation was extrapolated), while a good match was obtained at higher gas velocities. The experimental findings reported in this paper indicate that the novel IR/DIA technique can successfully be applied for mass transfer and gas mixing studies in gas–solids multiphase flows.
      Graphical abstract image

      PubDate: 2014-06-14T14:56:44Z
       
  • Modelling of the interaction between a falling n-heptane droplet and hot
           solid surface
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Monica Gumulya , Ranjeet P. Utikar , Vishnu Pareek , Moses O. Tade , Subhasish Mitra , Geoffrey M. Evans
      Accurate prediction of the interactions between evaporating liquid droplets and solids are critical for many industrially important processes. A model based on coupled Level Set-Volume of Fluid approach was developed to simulate the interaction of evaporating liquid droplets with hot solid surfaces. The model incorporates appropriate source terms in the multiphase calculations to account for the heat and mass transfer. Accurate and stable numerical procedure was developed and incorporated in open source solver OpenFOAM. A brief discussion on the model development along with several key issues that are associated with this process was presented. The resulting numerical model was validated through the experimental data of Chandra and Avedisian (Chandra, S., Avedisian, C.T., 1991. Proc. R. Soc. Lond., Ser. A 432, 13–41). Although some discrepancies were found between the numerical results and experimental data, the model was found to be capable of reproducing the reduced droplet spreading rate as the temperature of the surface is increased away from the saturation temperature. The decrease in rate of surface wetting results from the combined effects of surface tension, viscous forces and evaporation at the liquid-solid-vapour contact line. Further, the effects of increased pressure at the solid-liquid interface resulting from the rapid evaporation of the liquid, which in some cases can be quite severe such that the liquid gets lifted-off from the surface, were also captured, in good agreement with experimental observations. Finally, the effects of the solid temperature on the evaporation and heat transfer rates of the droplets were presented and analysed.


      PubDate: 2014-06-14T14:56:44Z
       
  • Vortical structures swept by a bubble swarm in turbulent boundary layers
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Hyun Jin Park , Yuji Tasaka , Yuichi Murai , Yoshihiko Oishi
      Bubbles injected into a wall turbulent boundary layer can modify heat, mass, and momentum transfers of the wall. One factor responsible for the phenomenon is alternation of the vortical flow structures near the wall. To demonstrate this graphically, we directly visualized the interaction between the vortical flow structures and a bubble swarm composed of bubbles with various sizes, by means of two-color laser-sheet illumination of the wall turbulence with a dilute suspension of flakes. Image processing realized quantitative characterization of interaction events in the buffer and logarithmic layers, referring to multiple measured quantities such as the relative advection velocity between bubbles and turbulence, spacing of vortices both in streamwise and spanwise directions, persisting lengths of vortices in both directions, and statistical inclination angles of the streamwise vortices. A particular finding from the present visualization is that the streamwise vortices in the buffer layer were swept by the bubble swarm but brought to the backside of the swarm to survive until the swarm passed by.


      PubDate: 2014-06-14T14:56:44Z
       
  • Numerical investigation of subgrid mixing effects on the calculation of
           biological reaction rates
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Marion Linkès , Pascal Fede , Jérôme Morchain , Philippe Schmitz
      The consequences of substrate concentration heterogeneities at the cell level, on the behavior of microbial populations have been identified some years ago. However, subgrid effects are rarely considered in bioreactor modelling. In this paper, this central issue is investigated with Direct Numerical Simulations (DNS) coupled with Lagrangian particle tracking and scalar field calculations in the case of statistically steady homogeneous and isotropic turbulence. From these calculations, the exact distribution of substrate uptake rates of a microorganism population is calculated and compared, favorably, to analytical solutions. A metabolic model considering anabolism, oxidative catabolism and dissimilation is invoked to quantify the consequences in terms of overall reaction rates at the population scale. It is shown that imperfect mixing reduces the growth rate and increases the by-product formation while leaving the total uptake rate unchanged. This work provides a rational explanation, based on physical consideration, for the loss in biomass productivity and the increase of by-product formation in imperfectly mixed bioreactors.


      PubDate: 2014-06-14T14:56:44Z
       
  • On ideal and optimum cascades of gas centrifuges with variable overall
           separation factors
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): V.D. Borisevich , M.A. Borshchevskiy , S. Zeng , D. Jiang
      It is demonstrated that the total flow in the optimum cascade composed of three different types of gas centrifuges with varied separative performance levels and overall separation factors varying over the cascade stages is less than that in the corresponding ideal (non-mixing) cascade. The data obtained make it possible to use the parameters of the optimum cascade to find the operational mode for the cascade stages that provides the minimum total flow in a separation cascade.


      PubDate: 2014-06-14T14:56:44Z
       
  • Empirical and physics-based mathematical models of uranium hydride
           decomposition kinetics with quantified uncertainty
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Maher Salloum , Patricia E. Gharagozloo
      Metal hydride particle beds have recently become a major technique for hydrogen storage. In order to extract hydrogen from such beds, it is crucial to understand the decomposition kinetics of the metal hydride. We are interested in obtaining a better knowledge of the uranium hydride decomposition kinetics. We first developed an empirical model fit to measurements compiled from different experimental studies in the literature and quantified the uncertainty resulting from the scattered data. We found that the decomposition time range predicted by the obtained kinetics is in a good agreement with published experimental results. Secondly, we developed a physics-based mathematical model to simulate the rate of hydrogen diffusion in a spherical hydride particle during the decomposition. We used this model to evaluate the kinetics for temperatures ranging from 300K to 1000K while propagating parametric uncertainty. We have compared the kinetics parameters derived from the empirical and physics-based models and found that the uncertainty in the kinetics predicted by the physics-based model covers the scattered experimental data. Finally, we used the predicted kinetics parameters to simulate the effects of boundary resistances and powder morphological changes during decomposition in a continuum level model. We found that the phase change within the bed occurring during the decomposition accelerates the hydrogen flow by increasing the bed permeability, while the pressure buildup and the gap forming at the wall significantly impede the hydrogen extraction. We also found that there is significant uncertainty in the bed decomposition time at the lower range of the kinetics.


      PubDate: 2014-06-14T14:56:44Z
       
  • Scalability of mass transfer in liquid–liquid flow
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): A. Woitalka , S. Kuhn , K.F. Jensen
      We address liquid–liquid mass transfer between immiscible liquids using the system 1-butanol and water, with succinic acid as the mass transfer component. Using this system we evaluate the influence of two-phase flow transitions from Taylor flow to stratified flow and further to dispersed flow at elevated flow rates. In addition, we address the scale-up behavior of mass transfer coefficients and the extraction efficiency by using reactors on the micro- and the milli-scale. Flow imaging enables us to identify the different flow regimes and to connect them to the trends observed in mass transfer, and the obtained results highlight the dependence of mass transfer on flow patterns. Furthermore, the results show that on the milli-scale fluid–structure interactions are driving the phase dispersion and interfacial mass transfer, and such a reactor design ensures straightforward scalability from the micro- to the milli-scale.


      PubDate: 2014-06-14T14:56:44Z
       
  • Structure-dependent drag in gas–solid flows studied with direct
           numerical simulation
    • Abstract: Publication date: 6 September 2014
      Source:Chemical Engineering Science, Volume 116
      Author(s): Guofeng Zhou , Qingang Xiong , Limin Wang , Xiaowei Wang , Xinxin Ren , Wei Ge
      Quantification of drag F is critical to the simulation of gas–solid flows in both discrete particle models and two-fluid models. It is commonly accepted that for homogeneous flow the drag is a function of solid volume fraction ϕ and particle Reynolds number Re p (based on the mean slip velocity and particle radius). However, its adequacy for heterogeneous flows encountered more frequently is in debate yet. In this work, we reveal the strong structural dependence of the drag in both a simple case of two particles and a typical case with stepwise heterogeneity, demonstrating the necessity for a structure-dependent drag description. To quantify such dependence, flow past idealized static suspensions with linear heterogeneity is studied first, which confirms a general form F(Re p,ϕ, ∇ϕ ,θ) suggested previously, where θ is the angle between the gradient ∇ϕ and the mean slip velocity. In the studied range of 5<Re p<30, F depends linearly on Re p for a given static particle configuration. However, the concrete expressions are yet to be found. Then for dynamic gas–solid suspension, large-scale simulations enabled by supercomputing systems reveal a much more complicated dependen on one hand, the drag coefficients on individual particles scatter even in the absence of distinct heterogeneity; and on the other hand, with the presence of distinct heterogeneity, the drag predicted by Wen and Yu (1966) deviates significantly from the simulation value in both direction and magnitude. A purely bottom-up statistical approach to establish a drag correlation in this case seems difficult and a theoretical elucidation is needed.


      PubDate: 2014-06-14T14:56:44Z
       
 
 
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